1. Field of the Invention
The invention relates to mobile computing devices, and in particular, to normally open and normally closed RF MEMS (micro-electro-mechanical systems) switches used in mobile computing devices.
2. Introduction
Mobile computing devices, such as cellular phones, handheld computers, MP3 players, laptop computers, etc. are very pervasive computing devices. The mobile computing devices provide various features, such as communications, computing features, Internet access, playing music or video, etc.
It may be desirable to provide the mobile computing devices with multiband abilities, or to have tunable antenna structures included. A commonly employed technology to provide such multiband capabilities or tunable antennas is to use RF MEMS (micro-electro-mechanical systems) switches. Such switches are typically constructed of a same switch mechanism (typically electrostatic) and use RF transmission line techniques to divide the RF signal to each switch throw. Using this method, any high voltage converter circuit would have to be continuously operating to provide control voltages to close one of the switch throws to pass the RF signal, or to open others, depending on the switch throw design. For example, where the design uses all normally open switches, the converter circuit would need to continuously operate to keep one of the switch throws closed.
Such a converter circuit may typically be a DC-DC converter that is continuously operating. Such continuous operation creates a continuous power drain, which can be a drain on battery life in portable computing devices, for example. It would be advantageous to provide an RF MEMS switch design for use with mobile computing devices that would allow the drive circuit to be in an idle or off condition to save on battery life, while still providing the desired functionality.